Determining the fertiliser phosphorus requirements of intensively grazed dairy pastures in south-western Australia with or without adequate nitrogen fertiliser
M. D. A. Bolland A B D and I. F. Guthridge CA Department of Agriculture and Food, PO Box 1231, Bunbury, WA 6231, Australia.
B School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
C Department of Agriculture and Food, Manjimup Horticulture Research Institute, Locked Bag 7, Manjimup, WA 6258, Australia.
D Corresponding author. Email: mbolland@agric.wa.gov.au
Australian Journal of Experimental Agriculture 47(7) 801-814 https://doi.org/10.1071/EA05184
Submitted: 30 September 2005 Accepted: 14 December 2006 Published: 2 July 2007
Abstract
Fertiliser phosphorus (P) and, more recently, fertiliser nitrogen (N) are regularly applied to intensively grazed dairy pastures in south-western Australia. However, it is not known if applications of fertiliser N change pasture dry matter (DM) yield responses to applied fertiliser P. In three Western Australian field experiments (2000–04), six levels of P were applied to large plots with or without fertiliser N. The pastures were rotationally grazed. Grazing started when ryegrass plants had 2–3 leaves per tiller. Plots were grazed in common with the lactating dairy herd in the 6-h period between the morning and afternoon milking.
A pasture DM yield response to applied N occurred for all harvests in all three experiments. For the two experiments on P deficient soil, pasture DM yield responses also occurred to applications of P. For some harvests when no fertiliser N was applied, probably because mineral N in soil was so small, there was a small, non-significant pasture DM response to applied P and the P × N interaction was highly significant (P < 0.001). However, for most harvests there was a significant pasture DM response to both applied N and P, and the P × N interaction was significant (P < 0.05–0.01), with the response to applied P, and maximum yield plateaus to applied P, being smaller when no N was applied. Despite this, for the significant pasture DM responses to applied P, the level of applied P required to produce 90% of the maximum pasture DM yield was mostly similar with or without applied N. Evidently for P deficient soils in the region, pasture DM responses to applied fertiliser P are smaller or may fail to occur unless fertiliser N is also applied. In a third experiment, where the soil had a high P status (i.e. more typical of most dairy farms in the region), there was only a pasture DM yield response to applied fertiliser N.
We recommend that fertiliser P should not be applied to dairy pastures in the region until soil testing indicates likely deficiency, to avoid developing unproductive, unprofitable large surpluses of P in soil, and reduce the likelihood of P leaching and polluting water in the many drains and waterways in the region. For all three experiments, critical Colwell soil test P (a soil test value that was related to 90% of the maximum pasture DM yield), was similar for the two fertiliser N treatments.
Acknowledgements
The experiments were conducted on properties owned by the following farmers who helped in many ways: Wally Bettink, Michael Armstrong and Victor Rodwell. Technical assistance was provided by Peter Needs and David Tooke. Martin Staines, Peter Sale, Frank McKenzie, Cameron Gourley, Graeme Ward and Joe Jacobs helped design the experiments and helped to determine the experimental procedures used. Funds were provided by the Government of Western Australia and the Dairy Research and Development Corporation (now Dairy Australia) (project number DAW043). CSBP Ltd measured soil test P and concentrations of nutrient elements in pasture DM, and donated all the fertilisers used for the three experiments in this project. The Chemistry Centre (WA) measured soil properties. Leonarda Paszkudzka-Baizert measured dry matter digestibility, metabolisable energy and crude protein in DM. Positive comments and suggestions of two anonymous referees helped us to improve the paper.
Aufrere J, Michalet-Doreau B
(1988) Comparison of methods for predicting digestibility of feeds. Animal Feed Science and Technology 20, 203–218.
| Crossref | GoogleScholarGoogle Scholar |
Barrow NJ
(1975) The responses to phosphate of two annual pasture species. I. Effect of the soils’s ability to adsorb phosphate on comparative phosphate requirement. Australian Journal of Agricultural Research 26, 137–143.
| Crossref | GoogleScholarGoogle Scholar |
Barrow NJ, Mendoza RE
(1990) Equations for describing sigmoid yield responses and their application to some phosphate responses by lupins and subterranean clover. Fertilizer Research 22, 181–188.
| Crossref | GoogleScholarGoogle Scholar |
Bolland MDA, Guthridge IF
(2007) Responses of intensively grazed dairy pastures to applications of fertilizer nitrogen in south-western Australia. Australian Journal of Experimental Agriculture In press 47,
Colwell JD
(1963) The estimation of phosphorus fertiliser requirements of wheat in southern New South Wales by soil analysis. Australian Journal of Experimental Agriculture and Animal Husbandry 3, 190–197.
| Crossref | GoogleScholarGoogle Scholar |
Colwell JD
(1965) An automatic procedure for the determination of phosphorus in sodium hydrogen carbonate extract of soil. Chemistry & Industry 1965, 893–895.
Davison TM,
Orr WN,
Silver BA,
Walker RG, Duncalif F
(1997a) Phosphorus fertiliser for nitrogen fertilised dairy pastures. 1. Long term effects on pasture, diet and soil. Journal of Agricultural Science, Cambridge 129, 205–217.
| Crossref | GoogleScholarGoogle Scholar |
Davison TM,
Orr WN,
Doogan V, Moody P
(1997b) Phosphorus fertiliser for nitrogen fertilised dairy pastures. 2. Long term effects on milk production and a model of phosphorus flow. Journal of Agricultural Science, Cambridge 129, 219–231.
| Crossref | GoogleScholarGoogle Scholar |
Earle DF, McGowan AA
(1979) Evaluation and calibration of an automated rising plate meter for estimating dry matter yield of pasture. Australian Journal of Experimental Agriculture and Animal Husbandry 19, 337–343.
| Crossref | GoogleScholarGoogle Scholar |
Eckard RJ
(1989) The response of Italian ryegrass to applied nitrogen in the Natal Midlands. Journal of the Grassland Society of Southern Africa 6, 19–22.
Eckard RJ, Franks DR
(1998) Strategic nitrogen fertiliser use on perennial ryegrass and white clover pasture in north-western Tasmania. Australian Journal of Experimental Agriculture 38, 155–160.
| Crossref | GoogleScholarGoogle Scholar |
Isaac RA, Johnson WC
(1976) Determination of total nitrogen in plant tissue, using a block digestor. Journal of Association of Official Analytical Chemists 59, 98–100.
McKenzie FR
(1996) The influence of applied nitrogen on herbage yield and quality of Lolium perenne L. pastures during the establishment year under subtropical conditions. South African Journal of Plant and Soil 13, 22–26.
McKenzie FR,
Jacobs JL, Kearney G
(2006) Effects of spring grazing on dryland perennial ryegrass/white clover dairy pastures. 1. Pasture accumulation rates, dry matter consumed yield, and nutritive characteristics. Australian Journal of Agricultural Research 57, 543–554.
| Crossref | GoogleScholarGoogle Scholar |
McQuaker NR,
Brown DF, Kluckner PD
(1979) Digestion of environmental materials for analysis by inductive plasma-atomic emission spectrometry. Analytical Chemistry 51, 1082–1084.
| Crossref | GoogleScholarGoogle Scholar |
Nelder JA, Mead R
(1965) A simplex method for function minimisation. The Computer Journal 7, 108–113.
Ozanne PG,
Keay J, Biddiscombe EF
(1969) The comparative applied phosphate requirements of eight annual pasture species. Australian Journal of Agricultural Research 20, 809–818.
| Crossref | GoogleScholarGoogle Scholar |
Ulrich A
(1952) Physiological basis for assessing the nutritional requirements of plants. Annual Review of Plant Physiology 3, 207–228.
| Crossref | GoogleScholarGoogle Scholar |
Walkley A, Black IA
(1934) An examination of the Degtjareff method for determining soil organic matter and a proposed modification of the chromic acid titration method. Soil Science 37, 29–38.
| Crossref | GoogleScholarGoogle Scholar |
|
